Coronavirus restrictions: Experts say mystery cases key to when restrictions will ease
It’s the “magic” number every Victorian wants to know. So just how low do case numbers need to go before coronavirus restrictions can be eased?
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Twenty may be the magic number of new daily coronavirus cases Victoria must reach before restrictions are eased.
One infectious diseases physician predicts new case numbers will reach single digits by the weekend.
But experts stress it’s vital mystery transmissions stay low before health orders can be wound back.
Deakin University Prof Catherine Bennett said 20 new daily cases could be a trigger to ease restrictions but only if there weren’t significant mystery cases, which is where the origins of infection are unknown.
These had been making up about 20 per cent of all coronavirus cases.
“I think it’s going to be based on the mystery cases more than the overall number,’’ Prof Bennett said.
“If we have got our overall numbers down to 20 — that might have the government feeling confident enough that they can manage that and we can open up.
“If we’ve got 20 cases overall but they’re all mystery cases and we’re not sure where these cases are coming from they’d still be quite nervous.
“As soon as you relax restrictions if that virus transmission pathway is still there it will open up again.”
University of South Australia Prof Adrian Esterman — who has completed modelling showing Victoria’s new case numbers will fall to about 60 on Tuesday, 45 on Wednesday and single digits by the weekend — said case numbers had risen and fallen steeply and there was no reason why some restrictions couldn’t be eased now.
This could include low-risk changes in two-week blocks such as doubling the one-hour daily exercise limit and a friendship “bubble” for singles.
Measures like the curfew, which had stemmed big gatherings like parties, were still needed.
“What they’ve got to do is to maximise the things that will improve people’s mental health but minimise the risk of extra transmissions,’’ Prof Esterman said.
“If it was up to me I'd ease restrictions now in the very fact of just allowing people to exercise more.
“We are down now to 70 cases. My key cut off was 200 cases a day because above that people doing the contact tracing simply couldn’t manage.”
University of Melbourne Prof Nancy Baxter said Victoria appeared to be aiming for a mix of virus suppression and elimination.
“It’s very low numbers — I think they’re just going to very slowly open up,’’ Prof Baxter said.
“They may well open up before they’re at 50 but it will be just very selective openings.
“There is no magic number. It all depends on where new cases are coming from. The cases we are seeing today reflect a virus that was contracted at least a week ago. They could open up when the case numbers that they have are a little higher because they know that’s going to come down even further. That’s why they don’t need to wait for it to be zero.”
Australian National University Prof Peter Collignon said analysis showed as many as one in every 500 people in Victoria had been unwittingly infected.
This compared with one in 100,000 in NSW.
“The key around Australia is the community cases with no obvious contact with a known case,’’ Prof Collignon said.
“I always assume for every one case there’s at least a couple of others you haven’t found yet. They are the most important numbers in my view.”
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